The overall goal of the Pharmacology Program are threefold. (1) Following determination of a compound's ability to selectively and specifically inhibit Src, rapid assessment of compound stability in tissue culture medium (and mouse and human plasma) will assist with selection of relatively stable compounds for cell culture cytotoxicity studies. Compounds that are unstable in these biological matrices would not be expected to exhibit adequate antitumor efficacy; this will prevent costly unproductive in vitro and in vivo experiments yet at the same time permit chemical modification of otherwise active leads. (2) The Pharmacology program is to provide rapid assessment of the relatively ability of a compound to cross cell membranes. Because we seek compounds which have intracellular targets (as opposed to membrane bound targets), they must be able to gain ready access to intracellular sites. In addition, to be useful in the clinic, lead compounds must also possess good oral bioavailability. Traditionally, measurement of drug egress across cell membranes has been accomplished with the epithelial Caco cell system. While this model has served well in the past, we will compare data derived from this system to that obtained using a new IAM.PC (immobilized artificial membrane-phosphatidyl choline) chromatography method. The later method has the capability of providing a much higher throughout than that which is capable with the Caco cell system. (3) The Pharmacology Program is to provide pharmacologic expertise early in the proposed animal studies as well as provide a resource for determination of pharmacokinetic parameters and drug metabolism. Initially, a formulation suitable for oral administration will be chosen for lead compounds selected for antitumor evaluations in mice. Then, we will make a preliminary assessment of bioavailability in vivo. Blood levels following oral administration will be determined at key time points. This information will be used as a guide to selection of dose and scheduling of the compounds. Compounds subsequently demonstrating good antitumor efficacy, will undergo full assessment of their oral bioavailability, pharmacokinetic parameters as well as metabolism if deemed appropriate.